A company in which Microsoft has a financial interest is suing Apple, claiming it infringes eight wireless communications-related patents.
Luxembourg-based Core Wireless Licensing SARL says in its lawsuit, filed in Eastern Texas District Court, that the iPad and iPhone are infringing patents it holds related to 2G, 3G, and 4G communication protocols.
Core Wireless holds up to 2,000 patents originally filed by Nokia, and was bought last year by Canadian firm Mosaid Technologies - now owned by US private equity firm Sterling Partners.
When Microsoft then licensed those patents, says the Wall Street Journal, it was given a share of future revenue that Mosaid received from the licensing of the patents to others.
The lawsuit may be something of an embarassment for Microsoft, as it rcently teamed up with Apple, as well as others, to buy up several thousand patents from Nortel Networks.
The company's been trying to position itself as occupying the moral high ground in the patent arena, recently declaring that it would negotiate to license patents it owns, rather than pursuing possible infringers through the courts.
In fact, though, the situation is out of Microsoft's control. The terms of Core Wireless's purchase of the patents mandate that it has to raise what money it can from them, returning two thirds to Microsoft and Nokia.
Indeed, Core Wireless is required to hit certain targets in terms of royalty payments, or else hand the patent rights back to Nokia and Microsoft.